Dynamic control systems for automotive vehicles have recently begun to be offered on various products. Dynamic control systems typically control the yaw of the vehicle by controlling the braking effort at the various wheels of the vehicle. Yaw control systems typically compare the desired direction of the vehicle based upon the steering wheel angle and the direction of travel. By regulating the amount of braking at each corner of the vehicle, the desired direction of travel may be maintained. Typically, the dynamic control systems do not address rollover of the vehicle. For high profile vehicles in particular, it would be desirable to control the rollover characteristic of the vehicle to maintain the vehicle position with respect to the road. That is, it is desirable to maintain contact of each of the four tires of the vehicle on the road.
Vehicle rollover and tilt control (or body roll) are distinguishable dynamic characteristics. Tilt control maintains the vehicle body on a plane or nearly on a plane parallel to the road surface. Roll over control is maintaining the vehicle wheels on the road surface. One system of tilt control is described in U.S. Pat. No. 5,066,041. The '041 patent uses control elements arranged between the vehicle wheel suspension members and the vehicle body to generate forces in a vertical direction. The control elements generate a rolling moment at the vehicle body counteracting the rolling motion caused by driving conditions. The rolling moment distribution is controlled between the front axle and the rear axle.
U.S. Pat. No. 5,046,008 is a similar device to that described in the '041 patent. This device is also specifically directed to minimizing the roll angle of the vehicle body using adjustable spring struts.
During certain vehicle maneuvers, the vehicle may not be in a turning or yawing condition but may be in a rollover condition. This situation may occur during a trip event. A trip event may occur when the vehicle slides laterally into an object such as a curb. Such a system does not address preventing rollover in a vehicle.
It would therefore be desirable to provide a roll stability system that detects a potential rollover condition as well as to provide a system not dependent upon a yaw condition.